title: Modified Gadonanotubes as a promising novel MRI contrasting agent.
abstract: OBJECTIVE
  Carbon nanotubes (CNTs) are emerging drug and imaging carrier systems which show significant versatility. One of the extraordinary characteristics of CNTs as Magnetic Resonance Imaging (MRI) contrasting agent is the extremely large proton relaxivities when loaded with gadolinium ion (Gdn3+) clusters.
  
  
  METHODS
  In this study equated Gdn3+ clusters were loaded in the sidewall defects of oxidized multiwalled (MW) CNTs. The amount of loaded gadolinium ion into the MWCNTs was quantified by inductively coupled plasma (ICP) method. To improve water solubility and biocompatibility of the system, the complexes were functionalized using diamine-terminated oligomeric poly (ethylene glycol) via a thermal reaction method.
  
  
  RESULTS
  Gdn3+ loaded PEGylated oxidized CNTs (Gdn3+@CNTs-PEG) is freely soluble in water and stable in phosphate buffer saline having particle size of about 200 nm. Transmission electron microscopy (TEM) images clearly showed formation of PEGylated CNTs. MRI analysis showed that the prepared solution represents 10% more signal intensity even in half concentration of Gd3+ in comparison with commerciality available contrasting agent Magnevist®. In addition hydrophilic layer of PEG at the surface of CNTs could prepare stealth nanoparticles to escape RES.
  
  
  CONCLUSIONS
  It was shown that Gdn3+@CNTs-PEG was capable to accumulate in tumors through enhanced permeability and retention effect. Moreover this system has a potential for early detection of diseases or tumors at the initial stages.
authors.affiliation: Department of Pharmaceutics, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran 14174, Iran. atyabifa@tums.ac.ir.
authors.forename: Rouzbeh
authors.initials: R
authors.lastname: Jahanbakhsh
authors.forename: Fatemeh
authors.initials: F
authors.lastname: Atyabi
authors.forename: Saeed
authors.initials: S
authors.lastname: Shanehsazzadeh
authors.forename: Zahra
authors.initials: Z
authors.lastname: Sobhani
authors.forename: Mohsen
authors.initials: M
authors.lastname: Adeli
authors.forename: Rassoul
authors.initials: R
authors.lastname: Dinarvand